Black raspberry extract may improve arterial stiffness in people at risk for heart disease, a new study finds.

Arterial stiffness is a general term for the elasticity (or compliance) of the arteries. The hardening or stiffening of the arteries is called arteriosclerosis. The stiffness of arteries influences how hard the heart has to work to pump blood through the body, and is considered an indicator of heart disease.

Researchers from Korea compared two groups with metabolic syndrome. Metabolic syndrome is a combination of conditions, which may include obesity, diabetes, high blood pressure, high cholesterol and elevated triglycerides.

The researchers divided 51 patients into two groups. Twenty six people received specially prepared 750 mg capsules of dried black raspberry extract for 12 weeks while the other 25 received a placebo.

The researchers looked at three biological indicators involved in arterial stiffness – central blood pressure, augmentation, and the amount of circulating endothelial progenitor cells. They found no change in central blood pressure, but the other two indicators were improved in the participants who had received the black raspberry extract capsules.  There was no improvement in the control group.

Black raspberries are considered healthful because of their high levels of antioxidants and anthocyanins, which are pigments that have been found to have disease-fighting properties.  While they are similar in appearance to blackberries, they contain more of these healthful substances.

While the sample was small and the researchers say they do not know how the black raspberry extract works, further research is warranted, the investigators say of their study, which appears in the Journal of Medicinal Foods.